The present invention relates generally to electrical generator/starters and air conditioning compressors, and more particularly, to an integrated electrical generator/starter and compressor device.
In current automotive applications, there are numerous components connected directly to the engine""s crankshaft that are required to perform the various vehicle functions. Three such components are the electrical generator/alternator, the air conditioning compressor, and the starter. The electrical generator/alternator uses an electric machine to generate the vehicle""s electrical energy. The compressor is driven by the crankshaft and is used by the HVAC system to cool the vehicle""s cabin. The starter is mounted on the rear of the engine block and is connected to the crankshaft through the flywheel or flexplate to start the engine. Each of these components adds mass, cost, and requires packaging space.
As manufacturers pursue improved fuel economy goals, a start/stop engine management concept has emerged. This approach enables the vehicle""s engine to be shut-off periodically during idle stop times, e.g., stop lights/signs, city traffic stop and go driving, and then re-started when requested by the driver (by e.g., actuation of the accelerator pedal). One such approach uses a generator/starter combination device.
However, some consideration must be given as to how cabin comfort is maintained during these engine off occurrences. Current technology uses an engine-belt drive compressor. When the engine is off, there is no power to drive the compressor and therefore cabin comfort suffers.
One solution is to simply request that the engine re-starts when cabin comfort, i.e., temperature, suffers. However, this approach will have a negative effect on fuel economy.
Another solution is to use a fully electrically drive compressor system which could be run at any time cabin cooling is required. However, this may also negatively affect fuel economy, in that the electric power is taken from the battery which must be charged via the alternator. There are significant efficiency losses associated with the electromechanical creation and use of this electrical energy.
The present invention is aimed at one or more of the problems, as set forth above.
In one aspect of the present invention an integrated electrical generator/starter and compressor device is provided. The device is adapted to be driven by a common drive shaft and includes an electrical generator/starter and a compressor. The electrical generator/starter is coupled to the drive shaft. The compressor is coupled to the electrical generator/starter and to the drive shaft and acts to pressurize a flow of refrigerant in response to rotation of the drive shaft. The electrical generator/starter is operable in first and second states. In the first state, the electrical generator/starter generates electricity in response to rotation of the drive shaft. In the second state, the electrical generator/starter utilizes electrical power from a battery to rotate the drive shaft.
In another aspect of the present invention, a system for use with an engine having a first drive shaft is provided. The system includes a clutch mechanism and a drive belt for coupling the first drive shaft and the clutch mechanism. A second drive shaft is coupled to the clutch mechanism. The clutch mechanism is adapted to controllably engage and release the second drive shaft thereby coupling and de-coupling the first and second drive shafts, respectively. An electrical generator/starter is coupled to the second drive shaft. A battery is coupled to the electrical generator/starter. A compressor is coupled to the electrical generator/starter and to the drive shaft and acts to pressurize a flow of coolant in response to rotation of the second drive shaft. The electrical generator/starter generates electricity in response to rotation of the second drive shaft while in a first state and utilizes electrical power from the battery to rotate the second drive shaft while in the second state. A controller is coupled to the electrical generator/starter, the compressor and the clutch mechanism and controls operation thereof in accordance of a plurality of modes of operation.
In still another aspect of the present invention, a method for controlling operation of an electrical generator/starter and a compressor for use with an engine having a first drive shaft is provided. The first drive is coupled to a second drive shaft by a clutch mechanism. The electrical generator/starter and the compressor are mechanically coupled to and integral with each other and coupled to the second drive shaft. The clutch mechanism is adapted to controllably engage and release the second drive shaft thereby coupling and de-coupling the first and second drive shafts respectively. The compressor is adapted to pressurize a flow of coolant in response to rotation of the second drive shaft, The electrical generator/starter is adapted to generate electricity in response to rotation of the second drive shaft while in a first state and for utilizing electrical power from a battery to operate the electrical generator/starter to rotate the second drive while in a second state. The method includes the steps of entering one of a first mode and a second mode, engaging the clutch mechanism and placing the electrical generator/starter in the second state in response to being in the first mode, and engaging the clutch mechanism and placing the electrical generator/starter in the first state in response to entering the second mode.